Inkjet printing is a well known in the art printing method. The basics of this technology are described, for example by Jerome L. Johnson “Principles of Non-impact Printing”, Palatino Press, 1992, Pages 302-336. ISBN 0-9618005-2-6. Commercial products such as computer printers, large format graphics printers and others exist.
An ink-jet print head consists of an array or a matrix of ink nozzles, with each nozzle selectively ejecting ink droplets. In order to achieve a higher print throughput and higher print resolution individual print heads or print head modules are assembled in arrays. In the context of the present disclosure an array is a one-dimensional or two-dimensional arrangement (assembly) of a number (a plurality) of print head modules.
The larger the number of print head modules of which the array is composed, the more difficult is it to ensure an even supply of ink to each of the print head modules. International Patent Cooperation Treaty Application PCT/JP2004/019809 to the same assignee teaches an ink jet array where inkjet print head modules forming the array, have one ink receiving port, and receive ink from an ink supply channel located below the port. This leads to a situation where the print head modules located along the ink supply channel and distanced from the ink inlet port receive diminishing amounts of ink. When the number of print heads exceeds 24 the array is made with two ink supply channels, although each print head receives the ink from one channel only.
Another problem associated with such arrays is evacuation of ingested or trapped air bubbles. Ingested air remains in the print head and suction needs to be applied in order to evacuate it. The ink enters the print head through arcaded tubing and air bubbles are trapped at the highest point of the arc changing the cross section available for ink conduction.